1. Field of the Invention
The invention relates in general to luminescent screens for picture display tubes and to a method for making such apparatus.
2. Description of the Prior Art
Multi-color luminescent screens are usually manufactured in a known fashion using a "slurry" photo technique method. Other proposals have also been advanced for applications for making flat picture display devices. German OS No. 28 04 127 which corresponds to U.S. Pat. No. 4,243,695 discloses a method of spraying which can only be utilized up to certain resolution limits with respect to the screen definition.
German OS No. 28 06 436 which corresponds to U.S. Pat. No. 4,243,735 and German OS No. 28 55 142 which corresponds to U.S. Pat. No. 4,325,002 disclose methods for the manufacture of conductive, mechanically stable luminescent screens particularly with black color spot borders which have worked satisfactorily and from which the present invention comprises an improvement.
German AS No. 25 40 132 which corresponds to U.S. Pat. No. 4,020,191 discloses a printing method which in addition to imprinting of luminophores additionally requires a photo technique for precise positioning.
Methods are known which are based on dusting or respectively brushing onto adhesive layers a luminescent powder wherein the adhesive layers have been selectively rendered "sticky" by exposure. See for example, British Pat. No. 2,111,233, German No. 29 34 929 which corresponds to U.S. Pat. No. 4,263,385.
Each of the above described methods and apparatus have disadvantages.